1. Field of the Invention
The invention relates to a vehicle hub unit in which a member that constitutes an inner ring is fixed by clinching to an end portion of a hub spindle of a hub wheel to which a wheel is fitted.
2. Description of Related Art
A hub unit is used to support a wheel of an automobile such that the wheel is rotatable with respect to a suspension. FIG. 4 is a sectional view that illustrates an example of an existing hub unit.
A hub unit 51 shown in FIG. 4 includes a hub wheel 53, an inner ring member 54, an outer ring 55, and a plurality of rolling elements 56. The hub wheel 53 has a hub spindle 52. The inner ring member 54 is fixed to one end of the hub spindle 52 by clinching. The outer ring 55 is arranged radially outward of the hub spindle 52. The rolling elements 56 are rollably arranged between one of outer ring raceways 55a of the inner peripheral surface of the outer ring 55, and an inner ring raceway 52a of the outer peripheral surface of the hub spindle 52 or an inner ring raceway 54a of the outer peripheral surface of the inner ring member 54. A flange portion 57 is formed at an end portion (left end portion in FIG. 4) of the hub wheel 53, and a wheel of a tire, a brake disc, and the like (not shown), are fitted to the flange portion 57. A fixing flange 58 is formed on the outer peripheral surface of the outer ring 55. In addition, the fixing flange 58 is used to fit the hub unit 51 to a vehicle body-side member (not shown) supported by a suspension of a vehicle.
Rotational driving force of a drive shaft 60 is transmitted to the hub unit 51 via a constant velocity joint 59. As one method of transmitting the rotational driving force, there is known a method in which, as shown in FIG. 5 in detail, a spline tooth portion (side face spline) 62 is formed at a clinched portion 61 of the hub spindle end portion for fixing the inner ring member 54, and then the spline tooth portion 62 is meshed with a tooth portion (side face spline) 64 formed at an end surface of the outer ring 63 of the constant velocity joint 59 (see, for example, Published Japanese Translation of PCT Application No. 2008-536737 and Japanese Patent Application Publication No. 2008-174178).
In the hub units described in Published Japanese Translation of PCT Application No. 2008-536737 and Japanese Patent Application Publication No. 2008-174178, rotational driving force is transmitted to the hub unit via a constant velocity joint due to the mesh of the teeth that extend in a direction substantially perpendicular to a rotary shaft.